Signal



March 13, 1934.` A. 1 MARTINEK ET A1.

SIGNAL` Filed May 12, 1930 2 Sheets-Sheet 1 INVENYOR-S ATTORNEYJ Mw M /vm Patented Mar. 13, 1934 PATENT OFFICE SIGNAL -Alois L. Martinek andArnold N. Taylor, Detroit,

Mich., assignors to C. M. Hall Lamp Company, Detroit, Mich., acorporation of Michigan Application May 12, 1930, Serial No. 451,745

4 Claims. (Cl. 88-1) The invention relates to light reflecting devicesadapted to be illuminated from an outside source of light. Moreparticularly the invention deals with a reector composed of a lighttransmitting material so constructed and arranged that part of the lightstriking the same is reflected back and part is transmittedtherethrough.

The object of the invention is to obtain a reflector of the abovedescribed type having a conj g figuration such as to lend itself readilyto inexpensive manufacturing processes. Another object of the inventionis to obtain a reflector having such a configuration that it may easilybe modified to obtain the desired proportion be- 1 5 tween the amount oflight reflected and the amount transmitted through the same.

These and other objects are attained by providing the novel constructionhereinafter set forth and illustrated in the accompanying drawings,wherein Figure 1 is a rear view of a reflector embodying our invention;

Figure 2 is an enlarged view showing the arrangement of prisms on therear side of the re- 3 ector;

Figure 3 is a cross `on the line 3 3 of Figure 2;

Figure 4 is a view similar to Figure 2 showing a modified constructiondesigned to reflect only a portion of the light; I

Figure 5 is a cross section on the line 5-5 of Figure 4^;

Figure 6 is a top plan view of a die or mold vfor casting the reflectorillustrated in Figure 2;

Figure '7 is a sectional View of the die shown in Figure 6 taken on theline 7--7 of Figure 6. Figure 7 is illustrative also of sections takenon the line '1a-'7a and '7b-719;

Figure 8 is a section through a lamp provided with the improvedreflector;v

Figure 9 is a section onrthe line 9-9 of Figure 6.

Figure 10 is a sectional view similar to Figure 7 showing the modifieddie for forming the modified reflector of Figure 1.

Referring now to the construction illustrated in Figures 1, 2 and 3, 10represents the reflector section of the reflector takenv The reflectorpreferably has a smooth front surface ll and a prismatic rear surface 12with a marginal portion 13 also forming a smooth surface. The roughenedportion 12 which is formed preferably by casting consists of a series ofindentations 14 and intermediate ridge portions 15 constructed andarranged in accordance with a predetermined geometrical patternhereinafter set forth.

Figuresu, 7 and 9 illustrate thedie or mold for casting of the reectorshown in Figure 2 and this die or mold 16 has a prismatic surface 17comp'emenlaryto the prismatic surface 12 of the reflector. The surface17 is formed by milling or otherwise c utting a series of parallelgrooves' 18 with a cutting tool 19 adapted to form a V-shaped slot, theopposite surfaces 20 and 21 of which are substantially apart. Thesurface 1'7 is also provided with a series of parallel grooves 22simillar to the grooves 18 but extending at an angle of 120 with respectto the grooves 18. A third set of parallel grooves 23 are formed in thesame manner at an angle of 120 with respect to the grooves Y22 and 18,respectively. This arrangement forms in the prismatic surface 17 aseries of pyramids 24,'each having its apex in a common plane and eachhavinga triangular base line in a plane parallel to the plane of theapexes. Each pyramid has three triangular faces and each face 25 isbounded by a base line 26 and two equal side lines 28, the base linebeing ,longer than the side lines.

The geometrical arrangement as above set forth forms the prismaticsurface into a series of prismatic faces 25, each of which extends at anangle of 90 with respect to the adjacent face in the next pyramid. Thusa light ray as represented by the arrow 29 traveling perpendicular tothe plane of the prismatic surface strikes a prismatic face 25 and. isreflected by said surface to an adjacent prismatic face which it strikesat an angle of 45 and is therefore reflected away from the prismaticsurfacein a direction perpendicular to its plane as represented by thearrow 29a. Since the prismatic surface is entirely composed of a seriesof the prismatic faces all light striking the surface perpendicular tothe plane thereof will be reflected back. n

Since the prismatic surface 12 of the reiiector is formed from the dieor mold shown in Figure 6, the surface instead of having a series ofupstanding pyramids is provided with a series of inverted pyramidalrecesses 30 complementary in form to the pyramids. Therefore theappearance of the surface 12 from the rear side of the reector may bedescribed as a series of ridges 31 arranged at angles of 60 with respectto one another. Light striking this surface from the rear side of thereflector is not appreciably reflected because of the angulararrangement of the side of the ridges. However, light striking the frontsurface ll of the reflector will be transmitted into the transparentmaterial until it strikes the faces 32 defining the pyramidal recesses30 and will thereupon be reflected back in the same manner as lightstriking the prismatic surface 1'? of the die. Thus as illustrated inFigure 3, a beam 33 approaching the reflector in a perpendiculardirection will strike the face 32 and will be reflected to the adjacentface 32 and Will in turn be reflected by the last mentioned face in adirection parallel to the beam 331 as indicated by the arrow 34. Sincethe surface 12 consists entirely of the angularly arranged faces 32, alllight approaching the front face of the reflector in a perpendiculardirection will enter the transparent material and be reflected back.Where the material is a definite color the light reflected from thereflector will assume the same color and consequently a coloredreflector will appear to be illuminated with a colored light when it isplaced in the path of a beam of white light.

One of the uses of our improved reflectors is for tail lamps on vehiclesand as illustrated in Figure 8, the reflector 10 is placed in a lampcasing 35 which contains also an incandescent bulb 36. The reflectorthus encloses the lamp with the prismatic side l2 within the casing andthe smooth side 11 exposed to view. With this construction even thoughthe incandescent bulb is not lighted, the reflector 10 will neverthelessact as an illuminated signal whenever it is subjected to an outsidesource of light such, for example. as the beam from a headlamp ofanother vehicle. On the other hand, when the incandescent bulb 36 islighted the reflector will also act as an illuminated signal from thelight within the lamp which is transmitted through the same. Thecharacter of the prismatic surface 12 however is such that only a smallportion of thel light is transmitted through the reflector and when itis desired to increase the intensity of illumination due to theincandescent bulb a modified form of reflector may be used.

In this modified form the general geometric configuration is the same asshown in Figure 2 but each of the pyramidal recesses 30 terminatesbefore reaching the apex forming a flat triangular surface 37substantially parallel to the surface 11. Thus the light which strikesthis surface 37 instead of being reflected is transmitted directlythrough the glass'. The effect of this modification is to reduce theamount of illumination resultingfrom the reflection of light fromoutside of the lamp and to increase the amount of illumination due tothe incandescent bulb within the lamp. It will be understood that theamount of total area in the triangular surfaces 37 may be predeterminedwith respect tothe total area of the prismatic surface in order toobtain the desired results. In order to obtain the modied prismaticsurface the mold or die illustrated in Figures 6 and 7 has the apexportion of each pyramid removed as indicated by the dotted line 38, thusforming a truncated pyramid illustrated in Figure 10 with a flat topsurface 39.

It is to be understood that while in the preferred embodiment of theinvention the prismatic surface on the reflector is complementary to thedie so that the light must pass into the glass before it is reflectedback, the die itself can also act as a reflector when the light strikesthe same directly. Consequently, the geometrical configuration of thedie itself might be used as a reflector. Thus in the broader aspects,our invention contemplates a prismatic structure having the angulararrangement of the facets above set forth regardless of Whether thisrelationship provides upstanding pyramidal projections as in the die(Figures 6 and 7) or depressed pyramidal recesses as in the reflector(Figures 2 and 3).

What we claim as our invention is:

l. A reflector comprising a transparent disk having a plurality offacets grouped together into a .three-sided inverted pyramidalconfiguration. the facets of two adjacent inverted pyramids having anincluded angle of approximately 90 and the respective facets of eachinverted pyramid having an included angle greater than 90.

2. A reflector comprising a transparent disk havin'g a plurality offacets grouped together into a three-sided inverted pyramidalconfiguration, the facets of two adjacent inverted pyramids having anincluded angle of approximately 90 and the facets of each invertedpyramid having an included angle of 45 with respect to the plane of thebase.

3. A reflector comprising a transparent disk having a series ofpyramidal recesses in one side thereof, each recess being defined bytriangular facets arranged in a predetermined angular relationship, thefacets .of adjacent recesses havv ing an included angle of substantially90.

4. A lens having on one side a plurality of inverted V-shaped ridgeshaving included angles ALOIS L. MARTINEK. ARNOLD N. TAYLOR.

